Multicolour tunable luminescence of thermal-stable Ce3+/Tb3+/Eu3+-triactivated Ca3Gd(GaO)3(BO3)4 phosphors via Ce3+ → Tb3+ → Eu3+ energy transfer for near-UV WLEDs applications

A series of single-component blue, green and red phosphors have been fabricated based on the Ca3Gd(GaO)3(BO3)4 host through doping of the Ce3+/Tb3+/Eu3+ ions, and their crystal structure and photoluminescence properties have been discussed in detail. A terbium bridge model via Ce3+ → Tb3+ → Eu3+ energy transfer has been studied. The emission colours of the phosphors can be tuned from blue (0.1661, 0.0686) to green (0.3263, 0.4791) and eventually to red (0.5284, 0.4040) under a single 344 nm UV excitation as the result of the Ce3+ → Tb3+ → Eu3+ energy transfer. The energy transfer mechanisms of Ce3+ → Tb3+ and Tb3+ → Eu3+ were found to be dipole-dipole interactions. Importantly, Ca3Gd(GaO)3(BO3)4:Ce3+,Tb3+,Eu3+ phosphors had high internal quantum efficiency. Moreover, the study on the temperature-dependent emission spectra revealed that the Ca3Gd(GaO)3(BO3)4:Ce3+,Tb3+,Eu3+ phosphors possessed good thermal stability. The above results indicate that the phosphors can be applied into white light-emitting diodes as single-component multi-colour phosphors.